Android获取文件的MD5

节选自：Android获取文件的MD5

private void getFile(){
        String path = Environment.getExternalStorageDirectory().getAbsolutePath();
        Log.d("ATG", path);
        File file = new File(path+"/e8706cf83a2cda33dae5c40025922d75.apk");
        String md5 = getFileMD5(file);
        Log.d("ATG", md5);
    }

    public static String getFileMD5(File file) {
        if (!file.isFile()) {
            return null;
        }
        MessageDigest digest = null;
        FileInputStream in = null;
        byte buffer[] = new byte[1024];
        int len;
        try {
            digest = MessageDigest.getInstance("MD5");
            in = new FileInputStream(file);
            while ((len = in.read(buffer, 0, 1024)) != -1) {
                digest.update(buffer, 0, len);
            }
            in.close();
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
        return bytesToHexString(digest.digest());
    }

    public static String bytesToHexString(byte[] src) {
        StringBuilder stringBuilder = new StringBuilder("");
        if (src == null || src.length <= 0) {
            return null;
        }
        for (int i = 0; i < src.length; i++) {
            int v = src[i] & 0xFF;
            String hv = Integer.toHexString(v);
            if (hv.length() < 2) {
                stringBuilder.append(0);
            }
            stringBuilder.append(hv);
        }
        return stringBuilder.toString();
    }